[jdk11u-dev] RFR: 8230808: Remove Access::equals()

[Aleksey Shipilev]

This is the first patch in the series to cleanup/revert the GC BarrierSets to most current state. See the dependent ("this issue blocks" links) issues to see what is next.

The `equals` APIs were added for Shenandoah GC, in the incarnation that exposed both from- and to-copies to the runtime system (see JDK-8199781). Since then, Shenandoah greatly simplified this by switching to a strong to-space invariant, which obviates the need for this API. Therefore, it was removed in JDK 14. This patch reverts JDK 11 parts to that shape as well, which should simplify 11u maintenance.

Additional testing:
 - [x] Linux x86_64 {release, fastdebug, slowdebug} builds
 - [x] Linux x86_64 `tier1`, `tier2` with Shenandoah, Parallel

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Commit messages:
 - 8230808: Remove Access::equals()

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/100/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=100&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8230808
  Stats: 104 lines in 6 files changed: 0 ins; 102 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/100.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/100/head:pull/100

PR: https://git.openjdk.java.net/jdk11u-dev/pull/100